Self-synchronous controlled motor system



8- 1, 1948. w., c. GRABAU 2,448,025

SELF-SYNCHRONOUS CONTROLLED MQTOR SYSTEM Filed July 9, 1942 2 Sheets-Sheet l INVENTOR WILLIAM Cmusmn 6mm 7 BY M HAND comm- F|G. 1 :11am

Aug. 31, 1948. c GRABAU 2,448,025

SELF-SYNCHRONOUS CONTROLLED MOTOR SYSTEM 2 Sheets-Sheet 2 Filed July 9, 1942 FOR omzmou 60 62 2 POSiTlON OFWTOR commuxq a! TOOL r/////////////////// /'////li FIG 5 INVENTOR WILLIAM Cumsnm 6mm ATTORNEY Patented Aug. 31, 1948 UNITED STATES SELF-SYNCHRONIggSggONTROLLED MOTOR William Christian Grabau, Brighton, Mam, as-

signor, by mesne assignments, to Submarine Signal Company, Boston, Mass a corporation of Delaware Application July 9, 1942, Serial No. 450,329

6 Claims. (01. s1s-so The present invention relates to a training control system for rotatin and directing a rotatable element at varying speeds and to varying positions. The system is more particularly applicable to the control with the use of an alternating current source and may be applied for training searchlights, radio locators, signaling devices and guns.

One advantage in the present system is that great accuracy is obtained by the elimination of the lag or slack in the system, In the present application the training motor driving the element to be trained follows directly and without delay the training of the hand-controlled element. This, in part, is accomplished by the use of a balanced system in which current flows under normal operating conditions through the driving elements in both directions and the operation and drive are obtained by the increase of current' flow in one direction over that in the other direction so that there is no necessity and no time delay in the building up of the initial current flow in the circuit. This balancing effect is particularly important in the present application because the control must be able to rotate the training gear in what may be called a forward and a reverse direction.

Further advantage is obtained in the present system because of the rapidity of action between the operating hand control and the circuits controlling the driving machine as will be more clear- 1y understood from the description in the specification below. In this respect the present invention incorporates in part some of the features disclosed and cla med in my copending application Serial No. 432 982, filed March 2, 1942, now

Patent No. 2.352.626. issued July 4. 1944;

Further merits and advantages of the present invention will be .more clearly understood in connection with the drawings illustrating an embod ment of the invention in which Fig. 1 shows a dia rammatic arrangement-oi the invention; Fig. 2 illustrates a set of curves applicable to the operation of the circu t of Fig. 1; and Fig. 3 shows a mod fied application of the invention to a machine tool.

In the dra ing. the driving motor I represented at M may drive the training apparatus which may. of course. be a Searchlight, radio locator or submar ne signaling apparatus. Driven on the same shaft with the motor I is the self-synchronous repeater 2 with a stator 2' which is electrically connected with the self-synchronous generator stator 3 in which a voltage is induced by means of the winding 3' whose relative position with respect to stator 3 is controlled by the operating crank 4. This generator is, of course,

energized by an alternating current supply 5 in the usual manner. The rotor 8 of the motor 2 is relatively the same element as the rotor 3' so that when rotor 6 and the hand-operated rotor 3' have the same phase displacement, no voltage will be supplied to the output transformer Ill of the repeater system. Under this condition the voltage developed by the double rectifier 1 will be zero and therefore there will be no bias on the grids l3 and i8 from repeater 2 and the generator 3. When there is a displacement between 6 and 3'. a voltage is developed in the winding l0 and therefore the transformer is energized so that a voltage exists across both secondaries II and I2 in which case both grids l3 and ll of the double triode l5 and the grids l8 and ll of the double triode l3 will become negatively biased. When no bias exists on l3 and iii, a normal balanced condition prevails in which the driving motor i isat rest. The double triodes l5 and [8, which are preferably of the thermionic type, have their anode-cathode voltage supplied from the alternating current source i9 which may be the samealternating source as the source 5 through the transformer 20 which has several secondaries 2|, 22, 23, 24 and 25. The secondaries 2i and 25 suppLv, respectively, the cathode-anode voltages for the tubes i5 and i8 in a manner that will presentlybe described. For the tube IS the secondary winding 2i is connected in series with the primary 26 of a transformer 21. This primary winding 2. and the transformer winding 2! are in series with the cathode 28 and the anode 29 of the tube l5 while the secondary 30 of the transformer 21 is in series with the cathode 3| and the anode 32 of the tube IS. The same arrangement is applied to the tube iii, the trans- .former 33 operating in the same manner as the transformer 21 with a primary 34 and a secondary 35, the primary 34 being in the series circult with the cathode 3B and anode 31 while the secondary 35 is in series with the cathode 3'8 and the anode 39. When a normal current is flowing across the tube l5 between the anode 28 and the cathode 28, the voltage developed across the secondary 2| is partly distributed across the primary 28 of the transformer 21 and across the cathode-anode drop in the tube I5. Since the transformer 21 has approximately a one to one ratio, the same voltage is developed between the anode 32 and the cathode 3! as across the primary 28 of the transformer 21.

When the displacement of the winding 6 of the repeater motor varies with respect to that of the winding 3', a voltage will be generated across the transformer lll which will produce a voltage drop in the resistances 8 and 9 of the rectifier 1, and thereby increase the negative bias on the grids l3 and i l of the tube l5, and i6 and ll of the tube l8. Since the voltage is applied in opposite phases to the cathodeanode circuits of the tubes l5 and I8, this negatlve bias will tend to shut off the flow of curgaseous control tube 32.

.tion tube.

acsaoes decrease the voltage developed across the primary 28 or 34 of the transformer 27 or 88, re-

spectively, applying most of the voltage generated in the secondary winding 28- or 25 across the cathode-anode 28-2t or 36-37. This decrease in voltage in the transformer 21, for instance, will directly decrease the voltage applied between the cathode ill and the anode t2, and together with the increase in the negative bias .age. When-therais a displacement voltage in either direction, then the curve C or D is steepened and cuts the critical grid voltage curve earlier in the cycle, causing the conduction to fire over a longer period of the cycle. It should be borne in mind that the phases do not change but only their selection and magnitude which are dependent on the relative position oi the rotor 6 and rotor ti.

on the grid It will sharply decrease the cathodeanode current flowing between St and 82. The.

output of this tube flows through a resistancecondenser circuit to and M, respectively, the resistance of which controls the bias on the In a similar manner when the displacement between t and 3' is in the opposite phase, the control tube d8 has its bias 44 controlled by means of the resistance 45 and condenser 8% connected in shunt in the cathode-anode circuit 3tl39 of the tube it. The grids bl and 66 of the tubes 52 and 33, respectively, are therefore controlled by the output circuits of the tubes i5 and it, respectively, according to the direction of displacement and an increase in grid bias developed by an increase in a voltage output of the rectifier T will tend to decrease sharply the bias applied to the grids (W and Mi of the tubes 32 and 63, respectively, in the manner that has been described in my Patent No. 2,352,626 mentioned above. The slope oi this decaying voltage at one or the other of the grids til and it becomes steeper with increase of operating displacement voltage. The anode-cathode circuits of the control tubes :32 and 53 are supplied by means of the transformer 48, the secondaries (it and so of which supply respectively the tubes 32 and G8. Whenever the biases on the grids ill and i l decrease be-= low the critical value during the positive alter-' native voltage cycle on the tubes 52 and 38 respectively, the tubes will permit the flow of current and then the circuit is completed through the armature ofthe motor i and thereby the training gear may be turned in one direction or the other.

The direction of rotation of the motor l is governed by the relative positions of the rotor 8' of the self-synchronous generator 3 and the rotor t of the motor 2. The voltages impressed upon the cathode-anode circuits of the conduction tubes 62 and 53 as well as those impressed on the tubes 65 and iii are 180 degrees out or" phase with each other so that the biases on the grids ll and i l simultaneously operating in the same fashion will permit conduction only in one of the two conduction tubes. In one relative position of the rotor 3' and the rotor b, one decaying voltage either on the grid til or M will be altered by the change of displacement voltage produced in the resistances t or 9, in which case the voltage on the selected grid l'l or M will cooperate with the positive half cycle in one tube, whereas in the other relative position between the rotor 3' age on the other of the grids 77 or M will cooperate with the positi e voltage on its conduc- This is illustrated in Fig. 2. In this case A may represent the cathode-anode voltage applied across the tube 42 and B the cathode-anode voltage applied across the tube 43. The normal decaying voltage developed on the grids 41 and 44 is in the form shown in curve C or curve D, respectively, when there is no displacement voltand the rotor t, the volt-.

The potentiometer adjustments B8 and B6 are used to adjust the magnitude oi the voltage applied to the grids 41 and $41 as has been explained. These adjustments may be so made that the decaying grid voltage always permits a small amount of current to fiowat the endof each positive half cycle as illustrated by the shaded sections 3 in the figures of Curves A and B. This will provide a definite balance when the motor is not moving and has the effect of causing the motor to follow the training gear ac curately when the hand control turns the generator rotor 3' in either direction. In the present system the training gear will follow the' control even at very slow speeds with an accuracy of less than one-half a degree displacement between the control and the controlled element.

It will be noted by following through the circuit diagram that the secondary winding 49 is in series with the motor 9 and the tube 42 so that when the tube 62 fires, current will flow through the motor 0 in the direction of the arrow bi. It will also be noted that the winding is in series with the tube fill and the motor land that when the grid 3 8 permits this tube to conduct current, current will flow through the motor 3 in the direction of the arrow 52.

In Fig. 3 there is shown of the arrangement shown tn Fig. i. In this. case the self-synchronous control element is indicated at til. This is mounted to move with the movable tool element of the machine up or down according to the double-ended arrow lb. The rotor 6b, is provided with a shaft 6i which has a point 6% bearing on the surface @5 oi a movable template to which the movement of the angular position of the rotor till will be changed to the upward and downward bar lit, the tool following the it hasbeen brought to relatively t l. Under these at is raised. the

corresponding motion of the point td until the same position as the point circumstances when the bar displacement of the rotor til attached to the shaft 85 from a neutral position will bring about a movement of the tool and correspondingly of the whole motor tending to return the rotor the same angular displacement to its neutral position where it comes to rest. I

Since the magnitude of the displacement of the rotor with respect to its stator governs the amplitude of the voltage produced, the speed-oi rotation will be governed by the displacement between the rotor t0 and its stator. This will be evident from the circuit of Fig. .1. The rela tive displacement of the generator winding 8 with respect, to the winding 6 will produce relatively higher voltages developed across the resistances Band 9 and this will react to cause a quicker decay of the voltage in the resistors 40 and 45 and therefore permit conduction earlier in the cycle in one of the tubes 42 or 43. operative feature applies to Fig. 3 w crease in displacement caused by the bar 63 being carried higher by the era an 111- point 64 or surface of a special application r The same the template 9!, will produce a greater displacement voltage in the self-synchronous generator and therefore a higher speed acting on the tool to restore the elements to their neutral position.

Having now described my invention, 1 claim:

1. In a training control and follow-up system, gaseous conduction tube means having grid control elements, thermionic vacuum tube means and circuit operative to provide control 01 said grid control elements comprising double triode tube means having double anode and cathode elements, an alternating current source providing a potential across one set of anode and cathode elements dependent upon the conduction across the other set of anode-cathode elements, said double triode having grid control elements and means operative by said system for supplying a controlling voltage to said grid control elements for governing the conduction across said triode elements, and means in the output of said double triode tube means for controlling the potential applied to said grid control elements 01' said gaseous conduction tube means.

2. In a training control and follow-up system operable through an alternating current source providing a displacement alternating voltage for control and operation of the system, double triode tube means and circuits comprising two sets oi anode, cathode and grid control electrodes, means for impressing an alternating voltage across the first set or cathode and anode elements, means dependent on said alternating voltage impressed on the iirst set of cathode and anode elements for impressing a second alternating voltage on the second set or cathode and anode elements, said second alternating voltage having an increasing magnitude characteristic with the decreasing of said first alternating voltage, and means for con.- verting said displacement alternating voltage to direct current pulses and impressing the same on said triode grid elements for controlling the dew 0! current through said double triode tube.

3. In a training control operable through an alternating current source 'a displacement alternatin voltage for control and operation or the system, double triode tube means and circuits comprising two sets 0! anode. cathode and grid control electrodes, means for impressing on the anode-cathode circuit of the first triode circuit having a transformer in series connection in said circuit with a secondary in the anodecathode circuit 01 said second triode set, and means for converting said displacement alternating voltage to direct current pulses and impressing the same on said triode grid elements (or controlling the iiow of current through said double triode tubes.

trol and follow-up system pcovidirl a displacement alternating voltage for controllingtheoperationotthesystmapairoi double triode tube means prising two sets 0! anode. cathode trol electrodes, means ener l said grid control electrodes irom said displacement alternating voltage, means for impressing an alternating voltage source across each first set of cathode and anode elements oi said double triode tube means. means dependent upon said alternating voltage ior impressing a second alternating voltage on each of the second sets of cathode and anode ele ments. said second alternating voltage having an increasing magnitude characteristic with the decreasing of said first alternating voltage, a pair at gaseous conduction tubes having grid control ing on the anode-cathode and follow-up system I set an alternating voltage, said so element, and means elements, an alternating. current source adapted to provide a potential across said pair of gaseous conduction tubes in opposing phases, and means for impressing the output 01 said double triode tube means upon the grid control elements of said gaseous tubes whereby the direction or current in the training control system may be selected.

5. In a training control and follow-up system providing a displacement alternating voltage for control and operation 01 the system, double trlode tube means and circuits comprising two sets of anode, cathode and grid control electrodes, means for impressing on the anode-cathode circuit 0! the first triode set an alternating voltage, said circuit having a transformer in series connection in said circuit with a secondary in the anodecathode circuit of said second triode set, a shunt circuit comprising a condenser and resistance connected in series in the anode-cathode circuit of said second triode set, a gaseous conduction tube means for controlling the flow of current in one direction in said training control, said gaseous conduction tube means havinga grid control for controlling the potential or said grid control element by the voltage decay in said resistance member.

6. In a training control system, a training motor, gaseous conduction tube means having a pair or anodes, cathodes and grid control elements, means for applying an alternating voltage source in opposing phases to said conduction tube means in series with the training motor, a training member for providing adisplacement alternating voltage for controlling the direction of rotation of the training motor in a forward or reverse direction, double triode tube means and circuits comprising two sets of anodes. cathodes and grid control electrodes, means for impresscircuit of the firs triode set a direct current pulse, means dependent upon said pulse for impressing a second pulse or the second set of cathode and anode elements. said second pulse having an increasing magnitud characteristic with the decreasing of said firs pulse, means for converting said displacemen alternating voltage to provide said first-mentioned direct current pulses and impressing the same on said triode grid elements for controlling the flow of current through said double triode tube and means for impressing the output or said double triode tube on the grids or said conduction tube means for operating said training motor.

WILLIAII CHRISTIAN GRABAU.

. asrssaiscss crrsn The iollowing' references are of record in the file or this patent: v

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